Evaluation of the microbial community in industrial rye sourdough upon continuous back-slopping propagation revealed Lactobacillus helveticus as the dominant species

Abstract

Aims: To assess the structure and stability of a dominant lactic acid bacteria (LAB) population during the propagation of rye sourdough in an industrial semi-fluid production over a period of 7 months. Methods and Results: The sourdough was started from a 6-year-old freezedried sourdough originating from the same bakery. A unique microbial consortium consisting mainly of bacteria belonging to species Lactobacillus helveticus, Lactobacillus panis and Lactobacillus pontis was identified based on culture-dependent (Rep-PCR) and culture-independent [denaturing gradient gel electrophoresis (DGGE)] methods. Three of the isolated Lact. helveticus strains showed remarkable adaptation to the sourdough conditions. They differed from the type strain by the ability to ferment compounds specific to plant material, like salicin, cellobiose and sucrose, but did not ferment lactose. Conclusion: We showed remarkable stability of a LAB consortium in rye sourdough started from lyophilized sourdough and propagated in a large bakery for 7 months. Lactobacillus helveticus was detected as the dominant species in the consortium and was shown to be metabolically adapted to the sourdough environment. Significance and Impact of the study: The use of an established and adapted microbial consortium as a starter is a good alternative to commercial starter strains.

Lactic Acid Bacterium Population Dynamics in Artisan Sourdoughs Over One Year of Daily Propagations Is Mainly Driven by Flour Microbiota and Nutrients

“…Lactobacillus panis , Lactobacillus frumenti , Lactobacillus amylolyticus and Lactobacillus acetotolerans steadily dominated industrial French sourdoughs during 10 days of propagation (Vera et al, 2012). Lactobacillus helveticus , L. panis and L. pontis were stable during long-time sourdough propagation (Viiard et al, 2012). Even in this frame, it was found that rye sourdoughs propagated at room temperature harbored different ratios of bacterial species, depending on the season of sampling (Viiard et al, 2016).…”

House microbiotas as sources of lactic acid bacteria and yeasts in traditional Italian sourdoughs

“…Lactobacillus helveticus dominated in the lyophilized starte and industrial semifluid sourdough samples (Viiard et al, 2013). Indeed, the stability of the sourdough microbiota at artisan, large bakery and laboratory levels depends on a number of factors, including flour microbial composition, microbial interactions, composition of flour in terms of carbohydrates and free amino acids (FAA), endogenous enzymatic activities (e.g., amylase), specific technology parameters (e.g., leavening and storage temperature, pH and redox potential, dough hydration and yield, number of sourdough refreshment steps, fermentation time between refreshments, and the use of starters and/or baker's yeast), and bakery environment (Corsetti and Settanni, 2007;G€ anzle et al, 2007;G€ anzle and Vogel, 2003;Gobbetti et al, 2005;Hammes et al, 1996;Viiard et al, 2013). Obligately heterofermentative LAB were mainly correlated with flours (e.g., Triticum durum flour), showing high levels of maltose, glucose, fructose, and FAA (Minervini et al, 2012a).…”

“…Selected strains of Lactobacillus sanfranciscensis and Lactobacillus plantarum were lost during daily back-slopping performed at laboratory level while others persisted (Scheirlinck et al, 2008(Scheirlinck et al, , 2009Siragusa et al, 2009;Minervini et al, 2010). Lactobacillus helveticus dominated in the lyophilized starte and industrial semifluid sourdough samples (Viiard et al, 2013). Indeed, the stability of the sourdough microbiota at artisan, large bakery and laboratory levels depends on a number of factors, including flour microbial composition, microbial interactions, composition of flour in terms of carbohydrates and free amino acids (FAA), endogenous enzymatic activities (e.g., amylase), specific technology parameters (e.g., leavening and storage temperature, pH and redox potential, dough hydration and yield, number of sourdough refreshment steps, fermentation time between refreshments, and the use of starters and/or baker's yeast), and bakery environment (Corsetti and Settanni, 2007;G€ anzle et al, 2007;G€ anzle and Vogel, 2003;Gobbetti et al, 2005;Hammes et al, 1996;Viiard et al, 2013).…”

Evolution of Bacterial Consortia in Spontaneously Started Rye Sourdoughs during Two Months of Daily Propagation

“…However, Lactobacillus amylovorus, Lactobacillus fermentum, Lactobacillus helveticus, Lactobacillus panis, Lactobacillus pontis, and Lactobacillus reuteri have also been identified as dominant species in rye sourdoughs [4], [6]–[9]. Since rye flours have a generally higher extraction rate than wheat flours [5] rye sourdoughs are characterized by higher buffering capacity compared with wheat and spelt sourdoughs but also higher concentration of mannitol and amino acids [8], [10].…”